Multidirectional Instability

 

 

 

 

 

Definition

 

Instability in at least 2 planes

- postero-inferior

- antero-inferior

- antero-postero-inferior

 

Epidemiology

 

Recognised as a common problem 

- often misdiagnosed

 

Most patients athletic

- average age 24 years (15 - 54 years)

 

Aetiology

 

1.  Inherent ligament laxity > 50%

 

2.  Repetitive overuse with capsular stretch 

- microtrauma

 

3.  Macro-trauma < 50%

 

Pathology

 

Collagen abnormality

 

Increased joint volume 

- 2° enlarged inferior axillary capsular pouch

- patulous anterior and posterior

 

Often attenuated, broad rotator interval

 

History

 

Often bilateral

 

Instability of other joints

 

Feeling of shoulder "slipping down" while carrying heavy loads

- inferior instability

 

Often recurrent subluxation with minimal trauma

- sleeping

 

Shoulder pain

- fatigue 

- impingement type pain with overhead activities

 

Examination

 

Ligamentous laxity 75%

 

Inferior instability

- Sulcus Sign +

 

 

Anterior instability

- anterior draw

- anterior load and shift

- anterior apprehension, positive Jobe's relocation

 

Posterior instability

- posterior draw

- posterior load and shift

- posterior apprehension / jerk test

 

Xray

 

Traction xray

- patient standing with 5-10 kg in each hand

- Shows inferior subluxation of head

 

DDx of Inferior displacement of head

 

Torn superior rotator cuff

Suprascapular nerve palsy

Deltoid atony eg CVA

Deltoid / axillary nerve palsy

 

Management

 

Non-operative

 

Mainstay of treatment

- operative results poor

 

Physiotherapy

 

Minimum 12/12

- initial shoulder strengthening

- strengthen 3 parts of deltoid, cuff & scapular stabilisers

- specific programme with rope & pulleys

- combined with education program

- ~ 90 % success

 

Operative

 

Principles

- never operate on voluntary dislocator

- MDI surgery less successful than surgery for unidirectional instability

- cannot perform isolated anterior surgery

- bristow procedures etc fail as capsule remains redundant 

- anterior surgery may displace head posteriorly

 

MDI with traumatic anterior bankart

- new symptomatic instability on a background of ligamentous laxity / MDI

- MRA diagnosis of anterior bankart

- is reasonable to operate on patient with new traumatic anterior instability with labral tear

- issue is whether to combine with capsular shift

 

Options for MDI

 

1. Neer and Foster inferior capsular shift

2. Arthroscopic capsular plication

 

1.  Open Inferior Capsular Shift ~ Neer & Foster 1980

 

 

Principle 

- detach capsule from neck of humerus

- shift capsule superiorly to obliterate the inferior pouch

- decrease joint volume

 

Technique

 

EUA

- to confirm diagnosis

 

Deltopectoral Approach / Axillary fold

 

SSC

- must divide SSC separate to capsule

- need to leave capsule intact

- make horizontal incision in inferior border of SSC

- at muscular aspect

- insert curved artery forcep between SSC and capsule

- will exit at rotator interval

- insert medial stay sutures x 2 (use different colour to differentiate from capsular sutures)

- make vertical incision on artery forcep to avoid injury to capsule

 

T shape capsulotomy of capsule

- vertical component on humeral insertion

- transverse component to midpoint glenoid

- mark with pen first

- make vertical component on articular margin

- place inferior and superior stay sutures

- make horizontal incision

- creates superior and inferior capsular flaps

 

 

Inspect joint

- ensure no loose bodies

- repair bankart lesion if needed

 

Inferior capsular flap

- must sharp dissect capsule off inferiorly around humeral head

- protect AXN at all times

- do so by following articular margin around

- ER shoulder +++

- must get past 6 o'clock into posterior aspect

- check that traction on interior flap reduces inferior capsular pouch

 

Superior advancement inferior capsular flap

- tension on flap aimed at eliminating inferior pouch

- must reduce posterior capsular redundancy

- multiple 0 pull off stay sutures through flap and into remnant humeral tissue

- +/- anchors

- begin inferiorly, care with AXN

- cut and clip each sutures

- then tie all sutures togther at end

 

 

Check ER

- arm adducted, check ER 45^o

- arm abducted to 90^o, check ER 45^o

 

Superior flap sutured down over inferior flap

- again multiple 0 pull off sutures

- tie

- check ER as above

 

Check not too tight

- can dislocated posteriorly

 

Closure of RI

- check ER as above

 

Subscapularis tendon brought over & reattached to normal location

- check ER as above

 

Post op

- Arm immobilised in sling 6/52

- No sport for 9/12 

 

Results

 

Bigliani et al JBJS Am 2000

- 52 shoulders with open inferior capsular shift

- approach posterior or anterior depending on greatest instability

- 96% remained stable at average 61 months

- 60% excellent and 30% good results

- 70% athletes able to return to sport at same level

 

Ogilvie-Harris Br J Sports Med 2002

- contact athletes

- antero-inferior capsular shift in 37 with 3 recurrences (8%)

- posterior-inferior capsular shift in 16 with 2 recurrences (1 anterior / 1 posterior)(12%)

- 80% return to sport in antero-inferior capsular shift

- 75% return to sport in postero-inferior capsular shift

- only 17% return to sport if bilateral procedures

 

 

2.  Arthroscopic

 

Technique

 

EUA

 

View via posterior and anterosuperior portal

- labrum is attached

- capsule very lax

 

 

Anterior plication

- use shaver to create capsular stimulation

- don't remove or resect capsule

 

Option 1

- pass through capsule, then through labrum
- inferior suture first

- take bite of anterior inferior capsule with suture passer

- advance suture passer

- then pass separately through anterior labrum at a more superior level

- tie

- repeat x 2

 

 

 

 

Option 2

- anchor in glenoid

- pass stures throught capsule and labrum

 

 

Posterior plication

- camera inserted via anterior portal

- insert posterior cannula

- repeat inferior posterior sutures x 3

 

 

May suture rotator interval if needed

 

Results

 

Baker et al Am J Sports Med 2009

- 43 patients average age 19 years

- 86% return to sport

 

3.  Thermal Capsular Shrinkage

 

Recognised as poor procedure

 

Results

 

Miniaci et al JBJS Am 2003

- 19 patients with MDI

- 9 recurrent instability

- 4 had parasthesia in AXN, one had deltoid weakness, all resolved

- worse results in posteroinferior compared with anteroinferior